1. Field of the Invention
The present invention relates to an apparatus and method for transmitting image data.
2. Description of the Related Art
With recent improvements of performance in communication environment and data processing environment as a backdrop, a streaming technology for distributing multimedia data, such as movie images and audio data, in real time through a network is in practical use. The practical use of such a steaming technology enables a user to view broadband broadcasting on a live medium or a recorded medium and to view it on a recorded medium on demand.
For this service, a technology for correcting an error occurring in, for example, a communication path, at a receiving apparatus is important.
One example of the technology for correcting an error at a receiving apparatus is forward error correction (FEC). FEC is a technique of transmitting redundant data for use in error correction from an image data sender to a receiver and correcting an error of the image data using the redundant data at the receiver.
Japanese Patent No. 3831558, corresponding to U.S. Pat. No. 6,317,462, describes a technique in which an encoder splits a video signal into a high priority partition and a low priority partition, the high priority partition data with redundant data for use in error correction being added is transmitted, and the low priority partition data is transmitted without redundant data. In this technique, the distinction between the high priority partition and the low priority partition is determined by the frame type of each frame (inter-frame coding I frame, prediction P frame, and prediction B frame).
However, if an error occurs in data of a frame to which no redundant data for use in error correction is added, correction using redundant data cannot be performed, and this may result in a decrease in the image quality.
That is, if an error occurs in B-frame data that is determined as low priority in accordance with the frame type, for example, correction using redundant data cannot be performed, and this may result in a decrease in the image quality of a reproduced image.